The present invention relates to a part mounting apparatus for mounting a plurality of parts of different types respectively having different dimensions on a substrate, and a part mounting method.
A conventional part mounting apparatus employed in fabricating a flat panel display, such as a liquid crystal display panel, mounts filmy electronic parts (hereinafter referred to as xe2x80x9cfilm electronic partsxe2x80x9d) on a glass substrate.
In such a part mounting apparatus as shown in FIG. 12A (a part mounting apparatus according to the present invention), a film electronic part 32 held by a vacuum holding mechanism 10 by suction is carried by a moving mechanism, not shown, to an edge of a glass substrate 31. The glass substrate 31 and the film electronic part 32 are provided with alignment marks 33 and 34, respectively. An imaging device 35 forms an image of an image pickup region R including the alignment marks 33 and 34, and an image processor, not shown, processes an image signal provided by the imaging device 35 to recognize the respective positions of the glass substrate 31 and the film electronic part 32. The moving mechanism, not shown, corrects the position of the film electronic part 32 held by suction by the vacuum holding mechanism 10 relative to the glass substrate 31 on the basis of position data (FIG. 12B) provided by the image processor. The vacuum holding mechanism 10 presses the film electronic part 32 against the glass substrate 31, and the film electronic part 32 is bonded temporarily to the glass substrate 31 with a connecting member, such as an anisotropic conductive film, not shown. A heating and pressing unit, not shown, fastens the film electronic part 32 temporarily bonded to the glass substrate 31 permanently to the glass substrate 31.
When temporarily bonding the film electronic part 32 to the glass substrate 31, the vacuum holding mechanism 10 holding the film electronic part 32 must be operated with attention so that the vacuum holding mechanism 10 may not interfere with other film electronic parts which have been previously temporarily bonded to the glass substrate 31. If the vacuum holding mechanism 10 interferes with those film electronic parts previously temporarily bonded to the glass substrate 31, those film electronic parts are dislocated and cannot be accurately mounted on the glass substrate 31.
Therefore, it is the conventional way to take into consideration the widths of all kinds of film electronic parts 32 to be mounted on the glass substrate 31 and gaps between the adjacent film electronic parts 32 in determining the width of the vacuum holding surface of the vacuum holding mechanism 10 (hereinafter referred to as xe2x80x9cvacuum holding widthxe2x80x9d). More concretely, the vacuum holding width of the vacuum holding mechanism 10 is determined, for example, according to the smallest one of the widths of the film electronic parts.
In recent flat panel displays, to which the present invention is related, film electronic parts 32 of many types respectively having greatly different widths, such as indicated at 32a, 32b, 32c and 32d in FIG. 13, are mounted on a glass substrate 31. If the vacuum holding width of the vacuum holding mechanism 10 is determined on the basis of the width of the smallest film electronic part, such as a film electronic part 32a in FIG. 13, as shown in FIG. 14A, side parts of a large film electronic part having a big width, such as a film electronic part 32b shown in FIG. 13, are apt to be caused to droop by their own weight as shown in FIG. 14B during transfer. When carrying a warped or wavy large film electronic part 32b, warped or wavy side parts of the film electronic part 32b cannot be straightened as shown in FIG. 14C. When an image of a film electronic part 32b having drooping side parts or warped or wavy side parts by the imaging device 35 as shown in FIG. 15, the distance Wmxe2x80x2 between the images of the alignment marks 34 formed in opposite side parts of the film electronic part 32b is shorter than the distance Wm of the actual film electronic part 32b and, consequently, the position of the film electronic part 32b relative to the glass substrate 31 cannot be correctly adjusted.
The present invention has been made in view of such a problem and it is therefore an object of the present invention to provide a part mounting apparatus and a part mounting method capable of accurately mounting a plurality of film electronic parts of different types respectively having different sizes on a glass substrate.
According to a first aspect of the present invention, a part mounting apparatus for mounting an electronic part on a substrate includes a vacuum holding mechanism that holds an electronic part by suction; and a carrying mechanism that carries the electronic part held by the vacuum holding mechanism so as to press the electronic part against the substrate; wherein the vacuum holding mechanism is provided with a vacuum holding width adjusting mechanism that adjusts a vacuum holding width of the vacuum holding mechanism according to the width of the electronic part to be mounted on the substrate.
Preferably, in the part mounting apparatus in the first aspect of the present invention, the vacuum holding mechanism includes a support member, a fixed vacuum holding block fixed to the support member, and a moveable vacuum holding block that moves toward and away from the electronic part on the support member, both the fixed and the movable vacuum holding block have vacuum holding surfaces which come into contact with the electronic part, respectively, and the movable vacuum holding block is capable of being moved between a working position where the vacuum holding surface of the movable vacuum holding block is flush with the vacuum holding surface of the fixed vacuum holding block with respect to a direction along the width of the electronic part to hold the electronic part by suction, and a waiting position to which the vacuum holding surface of the movable vacuum holding block is retracted from the working position. Preferably, the vacuum holding mechanism includes a support member, a fixed vacuum holding block fixed to the support member, and a movable vacuum holding block that moves toward and away from the fixed vacuum holding block on the support member, both the fixed and the movable vacuum holding block have vacuum holding surfaces which come into contact with the electronic part, respectively, and the vacuum holding surface of the movable vacuum holding block can be positioned selectively at one of a plurality of working positions where the vacuum holding surface of the movable vacuum holding block is flush with the vacuum holding surface of the fixed vacuum holding block with respect to a direction along the width of the electronic part to hold the electronic part by suction.
Preferably, the part mounting in the first aspect of the present invention further includes a suction adjusting mechanism that adjusts the suction of at least either the fixed or the movable vacuum holding block according to the type of an electronic part to be mounted on the substrate. Preferably, the part mounting apparatus in the first aspect of the present invention includes a storage device storing electronic part mounting information, and a controller which controls the suction adjusting mechanism on the basis of the electronic part mounting information stored in the storage device.
According to a second aspect of the present invention, a part mounting method for mounting an electronic part on a substrate includes the steps of: adjusting the vacuum holding width of a vacuum holding mechanism according to the width of an electronic part; holding the electronic part by suction by the vacuum holding mechanism having an adjusted vacuum holding width; and moving the vacuum holding mechanism to press the electronic part held by suction by the vacuum holding mechanism against a substrate.
Preferably, the part mounting method in the second aspect of the present invention further includes the step of adjusting the suction of the vacuum holding mechanism according to the type of an electronic part to be mounted on the substrate.
According to the present invention, since the vacuum holding width of the vacuum holding mechanism is adjusted according to the width of a film electronic part to be mounted on a substrate, the vacuum holding mechanism does not interfere with film electronic parts previously bonded on the substrate when mounting a small film electronic part having a small width. Since the shapes of at least opposite lateral side parts of even a large electronic part having a big width are corrected when mounting the large electronic part, adverse influence of drooping, warping or waving of the film electronic part can be prevented. Thus a plurality of film electronic parts of different types respectively having different sizes can be accurately mounted on a glass substrate.
According to the present invention, an electronic part can be accurately mounted on a substrate by adjusting the suction of the vacuum holding mechanism according to the type of the electronic part to be mounted on a substrate.